Tailoring the pore structure modified with functional groups for superior CO2 adsorption capacity and the selectivity of separation

• A new low-cost material was proposed for highly selective adsorption of CO 2 . • Effects of functional groups and pore structure on CO 2 adsorption was illustrated. • Achieving higher adsorption selection and water resistance and chemical stability. • The material is green and cheap with simple and flexible preparation process. • The material has good application potential in the field of industrial CO 2 capture. In this work, the ultra-uniform amidated nitrogen (N)-doped carbon sphere (ANG-Cs) adsorbent with different pore sizes and modified by kinds of functional groups was developed for efficient carbon dioxide (CO 2 ) adsorption, simultaneously obtaining the excellent selectivity of CO 2 /N 2 from the simulated ultra-low emission flue gas. We fabricated the uniformly monodispersed glucose-based carbon microspheres via a creative ethanol-assisted hydrothermal method, and also systematically explored and discussed the relationship between porous structures functional alkaline-containing N-groups and CO 2 adsorption capacity. Impressively, the pore size distribution arranged from micro- to mesoporous region along with large surface area of 1217 m 2 /g, that is benefit for the adsorption of small acid gas like CO 2 . Moreover, the adsorption capacity of the optimized ANG-Cs reached 4.89 mmol/g under 298 K and 1 bar, and the predictable adsorption selectivity of pure CO 2 /N 2 was as high as 43 in the simulated ultra-low emission flue gas. More importantly, when compared with some advanced MOF-based adsorbents, ANG-Cs not only owns similar CO 2 adsorption performance, but also keeps higher water resistance, chemical stability and lower cost. Therefore, this promising ANG-Cs with green synthesis for the controllable CO 2 adsorption and separation pushes the progress in industry application of ultra-low emission gas.